Small halogenated methane, ethylene, and phosphorous compounds in the gas-phase will be illuminated with tunable vacuum ultraviolet radiation and X-rays at several synchrotron radiation facilities. X-ray absorption excites and/or ionizes core electrons, eventually producing unstable doubly charged ions which readily fragment into ion pairs. Ion-ion coincidence experiments will detect ion pairs resulting from single and multiple bond rupture of the doubly charged species. Results will help elucidate variations in molecular fragment- ation patterns induced by site-selective core electron excita- tion as a function of molecule size, halogen substitution, and excitation wavelength. This planning grant will provide funds for equipment, faculty and undergraduate research salaries, travel to synchrotron radiation facilities for collaborative experiments, and publication costs. During the grant period, setup and construction of the experimental apparatus at Carleton College will be nearly completed and will involve undergraduate research students. An in-lab electron gun used to simulate x-rays will be purchased and utilized to assemble and test the time-of-flight ion mass spectrometer. Collabo- ration with a colleague on experiments similar to those listed above will keep Dr. Ferrett involved with new experiments in her field while providing needed expertise in ion coincidence techniques. %%% Research Planning Grants enable women who have not had prior independent Federal research support to develop a competitive research project. This project involves the simultaneous detection of ions resulting from decomposition of larger doubly charged ions thus providing critical information about the nature of events taking place after site selective core electron excitation.